Whetting steel



June 20, 1961 l. BUCK 3 WHETTING STEEL Filed Dec. 8, 1958 2 Sheets-Sheet 1 INVENTOR.

l, BUCK June 2 1961 NG STEEL Filed Dec. 8, 1958 Un tfifd States, Patent 2,988,933 WHETTING STEEL Immanuel Buck, 9 Justinus-Kerner-Weg, Fellbach,

Baden-Wurttemberg, Germany Filed Dec. 8, 1958, Ser. No. 778,823

Claims priority, application Germany Dec. l9, 1957 3 Claims. (Cl. 76-84) The present invention relates to improvements in knife sharpeners and more particularly to a steel for whetting or honing knives and other cutlery as used especially by butchers, in households, in industry, and in agriculture.

Prior to this invention, such whetting steels were usually provided with longitudinal grooves. Although these grooves variedin design, number, and cross-sectional shape, they usually had sharp outer edges producing a cutting or scraping'eifect upon the blade to be sharpened. When the blade was pressed against these sharp edges, the keenest part of the blade was bent over and formed an undesirable burr or wire edge. This effect occurred regardless of whether the surface portions between the grooves of the whetting steel were disposed within the same plane, or, when the steel had an oval cross section within a slightly curved plane, or within an arc of a circle when the steel had a round cross section.

It is an object of the present invention toprovide a whetting or honing steel which prevents the formation of such a-burr or ;wire edgeand thus permits a blade to be sharpened to a microscopically sharp edge. In order to attain this'object, the outer surface of the whetting steel is provided with a plurality of longitudinal grooves which dividethe surface into a plurality of curved areas, each of which is curved in such a manner that at least twoof such areas have a common tangent.

This is not trueforthe grooved whetting steels such as were known prior to this invention. In those known 's'teeIs .which have. an ovalcross' section the longitudinal grooves divide the oval outer surface or profile of the steel into a plurality of curved sectors, all of which lie on two opposite substantially circular arcs, the concave sides of which face toward each other. With such an outer profile, no two curved sectors can mathematically ever have a common tangent.

The whetting steel according to the present invention, however, even though it might have an oval cross section is so designed that, although the apexes of all the curved sectors lie on two opposite, substantially circular arcs, the concave sides of which face toward each other, each individual sector has a smaller radius of curvature than the mentioned arcs which form the general outline of the steel. According to the invention it is not even necessary that the apexes of the individual curved sectors lie on such circular arcs, but only that each sector has such a curvature and is disposed in such a relation to the other sectors that at least two sectors will have a common tangent. Although these two or more sectors with a common tangent may be adjacent to each other, the present invention is not limited thereto since they may also be separated from each other by other curved or uncurved parts of the steel. Furthermore, the apexes of the various curved sectors do not have to be confined by an arc, but may also lie on a straight line.

Another preferred feature of the invention is that each groove, as seen in a cross section, gradually merges into the adjacent sectors, so that no sharp edge appears within the plane of the apexes of the curved sectors.

Prior to this invention, whetting steels have also been known which had a circular cross section and were either provided with a very large number of longitudinal grooves along their surface or only with four longitudinal grooves which were disposed at an angle of 90 toward each other. However, the curved sectors between the adja- Patented June 20,1961

cent grooves all lie on one and the same are, and the grooves separating the adjacent sectors form sharp edges which also lie on this arc. With such whetting steels, the blade of the knife or other implement to be sharpened may either engage with the steel at a single point like a tangent engages with a circle, namely, when the blade rests on a curved surface of the steel, or the blade may engage with two points of the steel, namely, with the two sharp edges defining a groove. In neither case is it possible to attain a really sharp cutting edge because in the first case the cutting edge or a burr thereon will be bent over and in the second case because the cutting edge will be drawn over sharp edges.

With a whetting steel according to the present invention, however, the blade is drawn only over curved surfaces and will then always engage with at least two such surfaces since they have a common tangent, and it may even engage simultaneously with more than two curved surfaces if they all have a common tangent. Thus, when a blade is being drawn over two or more curved surfaces of a whetting steel according to the invention, the effect produced is the same as if the blade were drawn simultaneously over two or more grooveless whetting steels. Contrary to the assumption in the past it has been found accordingto the invention that it is of a greater advantage if a blade is whetted on a steel which has no grooves than on a steel with grooves which are designed and disposed in the conventional manner and therefore have sharp edges along the whetting surface. This finding has now been applied to produce the whetting steel according to the invention which fully achieves the object which the known grooved whetting steels were intended to attain but never did attain, namely, that any stroke of the blade along the whetting steel will bring any part thereof successively into engagement with several parts of the whetting surface which are especially designed to accomplish the desired purpose, namely, with Pa t th u sharre s g- Although the grooves in the outer surface of the whetting steel may also extend at an acute angle to the longitudinal axis of the steel, this angle should according to the invention, be smaller than the rake angle at which the steel and the blade are usually held relative to each other during a sharpening operation.

These and further objects, features, and advantages of the present invention will become more apparent from the following detailed description thereof, particularly when read with reference to the accompanying drawings, in which- FIGURE 1 shows a plan view of a whetting steel according to the present invention;

FIGURE 2 shows another plan view taken at right angles to FIGURE 1;

FIGURE 3 shows an enlarged cross section of the whetting steel according to FIGURES 1 and 2;

FIGURE 4 shows a cross section similar to FIGURE 3, but showing a modification of the invention; while FIGURE 5 shows a partial plan view of a knife blade being sharpened on a whetting steel according to another modification of the invention which is provided with grooves extending obliquely to the longitudinal axis of the whetting steel.

Referring to the drawings, and as shown particularly in FIGURES 3 and 4 thereof, the whetting steel 2 according to the invention which is provided with a handle 1, preferably has a fiat oval cross-sectional shape. The two opposite main surfaces of steel 2 are each defined by a flat arc of a circle and are provided with longitudinal grooves 3 which divide the surface into a plurality of sections or areas 5a to 5k. Each of the curved boundary lines defining these sections 5a to 5k has a smaller radius of curvature than the flat arcs which define the a general outline of steel 2. As clearly indicated in FIG- URES 3 and 4, these curved boundary lines of sections a to 5k are curved and disposed adjacent to each other in such a manner that at least two of these sections have a common tangent.

The two embodiments of the invention according to FIGURES 3 and 4 differ merely insofar from each other that in FIGURE 3, a straight knife edge may engage at the same time either with the sections 5a, 5b, and 5c or the sections 5a, 5d, and 5e, while in the modification of the invention as illustrated in FIGURE 4, the points of engagement of the curved surfaces 5 and 5g with the knife edge lie on a straight line, while another straight line even touches four curved surfaces, namely, 5f, 5h, 51', and 5k.

In either of the embodiments as illustrated in the drawings, grooves 3 which separate the adjacent sections 5 from each other are of a semicircular cross section and merge by gradually curved portions with the adjacent sections 5.

FIGURE 5 finally shows a portion of a whetting steel 2 which is provided with grooves 3 which extend at an angle a relative to the longitudinal axis of steel 2. This angle on should be smaller than the rake angle 13 at which the knife blade 6 is held relative to steel 2, that is, at the angle in which a knife is usually held while being sharpened on a whetting steel.

Although my invention has been illustrated and described with reference to the now preferred embodiments thereof, I wish to have it understood that it is in no way limited to the details of such embodiments, but that that it is capable of numerous modifications within the scope of the appended claims, especially insofar as it is not limited to the particular general oval cross-sectional shape of the whetting steel as shown or, for that matter, to any oval cross-sectional shape thereof, since it may also be of a generally flat, angular, circular, or square cross-sectional shape.

Having thus fully disclosed my invention, what I claim is:

1. A whetting steel for sharpening blades having a plurality of grooves in its outer surface extending substantially longitudinally of said steel, said grooves dividing said outer surface of said steel into a plurality of individually curved convex outer surface sections extending substantially longitudinally of said steel and each having a radius of curvature so that at least two of said surface sections have a common tangent, the walls of each of said grooves merging gradually into the adjacent surface sections.

2. A whetting steel for sharpening blades having at least one outer surface and a plurality of grooves in said surface extending at an acute angle to the longitudinal axis of said steel, said grooves dividing said outer surface of said steel into a plurality of individually curved convex outer surface sections extending at an acute angle to the longitudinal axis of said steel and each having a radius of curvature so that at least two of said surface sections have a common tangent, the walls of each of said grooves merging into the adjacent surface sections without forming any sharp edges.

3. A whetting steel for sharpening blades having a substantially oval general cross section and a plurality of grooves dividing the two opposite main outer surfaces of said steel into a plurality of individually curved convex outer surface sections extending substantially longitudinally of said steel and each having a radius of curvature smaller than the radius of curvature of each of said outer surfaces of said steel so that at least two of said surface sections have a common tangent, the walls of each of said grooves merging gradually into the adjacent surface sections.

References Cited in the file of this patent UNITED STATES PATENTS 221,540 Dow Nov. 11, 1879 852,873 Davidson May 7, 1907 1,394,927 Martin Oct. 25, 1921 2,816,351 Sauers Dec. 17, 1957 FOREIGN PATENTS 298,448 Great Britain Oct. 11, 1928 

